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QCSMA: Queuelength based CSMA/CA algorithms for achieving maximum throughput and low delay in wireless networks
 IN IEEE INFOCOM
, 2010
"... Recently, it has been shown that CSMAtype random access algorithms can achieve the maximum possible throughput in wireless ad hoc networks. However, the delay performance of these algorithms can be quite bad. On the other hand, although some simple heuristics (such as distributed approximations of ..."
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Cited by 64 (6 self)
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Recently, it has been shown that CSMAtype random access algorithms can achieve the maximum possible throughput in wireless ad hoc networks. However, the delay performance of these algorithms can be quite bad. On the other hand, although some simple heuristics (such as distributed approximations of greedy maximal scheduling) can yield much better delay performance for a large set of arrival rates, they may only achieve a fraction of the capacity region in general. In this paper, we propose a discretetime version of the CSMAtype random access algorithm that allows us to incorporate simple heuristics which lead to very good delay performance while retaining the throughputoptimality property. Central to our results is a discretetime distributed randomized algorithm that generates data transmission schedules according to a productform distribution, a counterpart of similar results obtained earlier for continuoustime models under the perfect CSMA assumption where collisions can never occur. An appealing feature of this algorithm is that it explicitly takes collisions into account during the exchange of control packets.
On the design of efficient CSMA algorithms for wireless networks
 In Proceedings of CDC 2010
, 2010
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Distributed CSMA/CA algorithms for achieving maximum throughput in wireless networks
 in Proc. Inf. Theory Appl. Workshop
, 2009
"... Recently, it has been shown that CSMAtype random access algorithms can achieve the maximum throughput in wireless ad hoc networks. Central to these results is a distributed randomized algorithm which selects schedules according a productform distribution. The productform distribution is achieved ..."
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Cited by 35 (1 self)
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Recently, it has been shown that CSMAtype random access algorithms can achieve the maximum throughput in wireless ad hoc networks. Central to these results is a distributed randomized algorithm which selects schedules according a productform distribution. The productform distribution is achieved by considering a continuoustime Markov model of an idealized CSMA protocol under which collisions cannot occur. In this paper, we present an algorithm which achieves the same productform distribution in a discretetime setting where collision of data packets is avoided through the exchange of control messages (however, the control messages are allowed to collide as in the 802.11 suite of protocols). In our discretetime model, each time slot consists of a few control minislots followed by a data slot. We show that two control minislots are sufficient for our distributed scheduling algorithm to realize the same steadystate distribution as in the continuoustime case. Thus, the overhead can be as low as twice the ratio of a control minislot to a data slot. 1
Maximizing Utility via Random Access Without Message Passing
, 2008
"... It has been an intensively soughtafter goal to achieve high throughput and fairness in wireless scheduling through simple and distributed algorithms. Many recent papers on the topic have relied on various types of message passing among the nodes. The following question remains open: can scheduling ..."
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Cited by 27 (4 self)
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It has been an intensively soughtafter goal to achieve high throughput and fairness in wireless scheduling through simple and distributed algorithms. Many recent papers on the topic have relied on various types of message passing among the nodes. The following question remains open: can scheduling without any message passing guarantee throughputoptimality and fairness? Over the last year, it has been suggested in three papers [1]–[3] that random access without message passing may be designed and proved to be optimal in terms of throughput and utility. In this paper, we first extend the algorithm in [2] and provide a rigorous proof of utilityoptimality for random access without message passing for Poisson clock model. Then we turn to the more difficult discrete contention and backoff model with collisions, study its optimality properties, and control a tradeoff between longterm efficiency and shortterm fairness that emerges in this model.
Queue BackPressure Random Access in MultiHop Wireless Networks: Optimality and Stability
"... A model for wireless networks with random (slottedAlohatype) access and with multihop flow routes is considered. The goal is to devise distributed strategies for optimal utilitybased endtoend throughput allocation and queueing stability. A class of queue backpressure random access algorithms ..."
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Cited by 17 (5 self)
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A model for wireless networks with random (slottedAlohatype) access and with multihop flow routes is considered. The goal is to devise distributed strategies for optimal utilitybased endtoend throughput allocation and queueing stability. A class of queue backpressure random access algorithms (QBRA), in which actual queue lengths of the flows in each node’s close neighborhood are used to determine the nodes ’ channel access probabilities, is studied. This is in contrast to some previously proposed algorithms, which are purely optimizationbased and oblivious to actual queues. QBRA is also substantially different from the well studied “MaxWeight ” type scheduling algorithms, which also uses backpressure. For the model with infinite backlog at each flow source, it is shown that QBRA, combined with simple congestion control local to each source, leads to optimal endtoend throughput allocation, within the network saturation throughput region achievable by random access without endtoend message passing. This scheme is generalized to the case of additional, minimum flow rate constraints. For the model with stochastic exogenous arrivals, it is shown that QBRA ensures stability of the queues as long as nominal loads of the nodes are within the saturation throughput region. Simulation comparison of QBRA and the queue oblivious optimizationbased random access algorithms, shows that QBRA performs better in terms of endtoend delays.
UtilityOptimal Random Access without Message Passing
, 2008
"... Random access has been studied for decades to achieve simple wireless medium access control (MAC). Some of the distributed scheduling algorithms for throughput or utility maximization also take the form of random access, although extensive message passing among the nodes is required. In this paper, ..."
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Cited by 17 (6 self)
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Random access has been studied for decades to achieve simple wireless medium access control (MAC). Some of the distributed scheduling algorithms for throughput or utility maximization also take the form of random access, although extensive message passing among the nodes is required. In this paper, we would like to answer this question: is it possible to design a MAC algorithm that can achieve the optimal network performance without message passing? We provide the first positive answer to this question in a simple Alohatype random access wireless adhoc network. In particular, we propose a distributed random medium access control algorithm based on the framework of network utility maximization (NUM). We prove the convergence of our algorithm for certain sufficient conditions on the system parameters, e.g., with a large enough user population. If each wireless node is capable of decoding the source MAC address of the transmitter from the interferring signal, then our algorithm indeed converges to the global optimal solution of the NUM problem. If such decoding is inaccurate, then the algorithm still converges, although optimality may not be always guaranteed.
EZFlow: Removing Turbulence in IEEE 802.11 Wireless Mesh Networks without Message Passing
"... Recent analytical and experimental work demonstrate that IEEE 802.11based wireless mesh networks are prone to turbulence. Manifestations of such turbulence take the form of large buffer buildup at relay nodes, endtoend delay fluctuations, and traffic congestion. In this paper, we propose and eva ..."
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Cited by 8 (4 self)
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Recent analytical and experimental work demonstrate that IEEE 802.11based wireless mesh networks are prone to turbulence. Manifestations of such turbulence take the form of large buffer buildup at relay nodes, endtoend delay fluctuations, and traffic congestion. In this paper, we propose and evaluate a novel, distributed flowcontrol mechanism to address this problem, called EZflow. EZflow is fully compatible with the IEEE 802.11 standard (i.e., it does not modify headers in packets), can be implemented using offtheshelf hardware, and does not entail any communication overhead. EZflow operates by adapting the minimum congestion window parameter at each relay node, based on an estimation of the buffer occupancy at its successor node in the mesh. We show how such an estimation can be conducted passively by taking advantage of the broadcast nature of the wireless channel. Real experiments, run on a 9node testbed deployed over 4 different buildings, show that EZflow effectively smoothes traffic and improves delay, throughput, and fairness performance. We further corroborate these results with a mathematical stability analysis and extensive ns2 simulations run for different traffic workloads and network topologies.
Random capture algorithms: Fluid limits and stability
 In Information Theory and Applications Workshop, February2010. 16
, 2003
"... Abstract—We introduce a distributed stateless MAC protocol referred to as Random Capture Algorithm (RCA) and analyze its performance in networks where interference is modeled by a contention graph. RCA does not require any message passing, nor transmitters to be aware of the content of their respect ..."
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Cited by 7 (1 self)
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Abstract—We introduce a distributed stateless MAC protocol referred to as Random Capture Algorithm (RCA) and analyze its performance in networks where interference is modeled by a contention graph. RCA does not require any message passing, nor transmitters to be aware of the content of their respective buffers. Yet, it achieves at least the same stability region as that obtained with maximal scheduling. We prove that RCA is actually throughput optimal in networks with Npartite interference graphs. We present simulation results that suggest that RCA is also throughput optimal on simple networks whose interference graphs are not Npartite. From there, it is tempting to conjecture that RCA are throughput optimal in all networks. I.
Convergence and tradeoff of utilityoptimal CSMA
, 2009
"... It has been recently suggested that in wireless networks, CSMAbased distributed MAC algorithms could achieve optimal ..."
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Cited by 6 (0 self)
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It has been recently suggested that in wireless networks, CSMAbased distributed MAC algorithms could achieve optimal